Cyclone filter

Hello Everyone:

I’m very new to the concept of wood gas.
I live in Las Vegas, NV.
I’ve started building a fire tube - but haven’t gotten far yet.
I’ll post pictures when I can.

Prior to joining this forum I read about imbert gasifiers. Many designs have cyclone filters.
It is a simple device, but I don’t see one on Wayne’s design.

Your thoughts here would be greatly appreciated.

Bryan Cox

There are a large variety of filter separators being tried/used by members here, including hot, cold, wet, dry, cyclone, scrubbers, bag house, and more. I have limited cyclone experience, and none with WG. If you type “cyclone” in the search box at the upper left you will see LOTS of discussion. Good luck.

Hi Bryan
I have built one on my stationary gasifier , it has a limited partical size collection capability.
The soot that is in the gas stream is so fine that it can’t be caught in a cyclone.
I have collected a 25 lt bucket of soot over the past few months and it weighs about 500grams!
Hope this helps
Thanks Patrick

I run an Imbert design with a cyclone and I was surprised at how much soot I got out of it. I see no reason why a WK design would be any different other that it appears they drop a lot of soot in the heat exchanger. If you could find room in-between the heat exchanger and the cooling rails it sure wouldn’t hurt anything. The WK do have to clean soot out of their cooling railsTomC

Patrick, what size is your cyclone?

Good morning Mr. Cox and welcome to the DOW ( driveonwood ) .

In the past Steve Unruh has made some excellent post on the cyclone vs drop box. . I looked back through the history last night but was unable to locate them .

For the cyclone to be effective it has to be close enough to the gasifier for the gas to remain hot . Condensation forms as soon as the gas cools.

I chose the drop box and heat exchanger for preheating the incoming air. With ether method soot will continue on to the motor but I haven’t seen any negative effects from the soot.

for the comments – I sincerely value your input !!

Hi Chris
I built two, the first is designed on a 4 in pipe or 100 mm.
The second is built on a 2in pipe or 50mm. The 4in cyclone was not collecting as much soot as I expected so I built the 2in one, I had one after the other. This was on my generator so it was running at constant speed but varing loads. The 2in did not collect any thing, the 4in collected about 2lt of soot running for 10 hours.
So this said to me that the 4in was very effective at collecting the soot that was heavy enough to drop out, the rest was too fine.
The soot I put in a bucket, if you pull your finger through the soot you can’t feel any resistance on your finger, there is no sensation on your skin, it’s like pulling your finger through air.
The soot flowes like water, it’s settles level in the bucket, if you breath to hard it puffs out in a big cloud and takes a long time to settle.
Thanks Patrick

I looked up cyclone in you tube and was fascinated with this Russian guy’s cyclone demonstration. It is a simple contraption that gives a visual view of it working with different size and weight particles. Unless you understand Russian you can just scroll through the parts where you see him talking to the camera and just watch when he is using it at about 4:35.

Don, That’s a great visual for doubters of the cyclone effectiveness. I’m planning on adding an oil bath air filter just before the engine somewhere. The gas will basically be blown down perpendicular to a pool of oil like in the old days. Drain plugs for oil changes.
Rosnovia, Pepe

Bryan and Patrick,
I used this diagram to build my cyclone and it works great.

Thanks Don; I liked the way he put a light behind of the funnel so we could see what is going on. I am a believer in cyclones. The one I have on my truck I have had to extend the “catch tank” twice and it still fills up very fast. My design would be similar to what Pepe posted above. One comment I would make is at some point in my research (?) they said the tube coming into the cyclone should be at an 11 degree angle downwards. This gentleman has his at an angle but it is much steeper. I would like to put another one in line on my truck but I’m not sure it would do any better. If I understand it, a lot of soot is dropped out as the gas cools. Mine is in the relatively hot gas to avoid moisture TomC

Thanks for the link, Don. That was a great demonstration. I almost stopped watching it at about 10 minutes when the guy walked away from the table.
But then he went on to vacuum his dirty floor and to suck up the dust while sheetrocking. At the end I saw a 5 second scene that was worth the time X10!: He had put a plastic bag into the collection pail under the cyclone separator. So he just pulled the full bag out of the pail for disposal.
I use a 30 gallon garbage can with a “cyclone” lid between my wood planer and my dust collector. It just never occurred to me to put the dang bag in there BEFORE I put the cover on. Instead, I always wrestle with the garbage can, trying to get all those shavings into a garbage bag without making a mess on the floor. In fact, why can’t I put a smaller garbage bag into my shop vac, for the same benefit too?----

Oh! Woodgas:
I use a GEK cyclone on the output of my JXQ-10 (wet cooler/filter). The gas temp is never above about 140 degrees F when it gets that far. I think it does a good job of collecting water condensation that otherwise would be getting to the engine. the liquid I collect contains some soot. Maybe I have said this earlier, but I just checked the plugs in my Onan 6.5NH genset and they are chocolate brown to white.

Pete Stanaitis

Do you have a better picture of that cyclone dimension that you posted? When I enlarge it so I can see it better it is so pixelated that I still can’t read the small characters.

That looks a lot like the GEK cyclone that I built a few years ago from their instructions and cad files.
Go Here:
You will find the cad files link about half way down the page. I didn’t check just now, but I think they have several versions, the handiest one being a simple pdf file that just about anyone can read.

FWIW, we didn’t have the capability to roll the cone with that small of a lower end ID, so we cut that part in half after cutting it out and after we realized the problem. Then we “rolled” each half in a sheet metal break by marking both small big ends about every 1/10th of the width, and bending a few degrees (18?) at each bend to form half circles. Then we welded to two halves together, Worked great. If that leaves anyone still wondering, I can add more.

One last thing about the GEK cyclone:
Later on I think they figured out that the cone shape really didn’t help much in their application, if at all, so now they just use a straight tube. If you look around their website, you should be able to find out about it.

I like the cone shape because it looks cool!

Pete Stanaitis

Hi Don,
Sorry about that poor quality, that’s the second time I’ve posted the “old” pic. Here’s a new one I think will be readable. It includes my specific dimensions which I am using for line D of the imbert dimensions. I started by calculating the cross sectional area of my gas exhaust from the gasifier and worked backwards to find “D”. I not sure how to exactly size a cyclone for bigger HP , but this works really well for my gasifier dimensions. I had an 8" fire extinguisher hanging out so that is what I used and lucked out well. Maybe someone can chime in on sizing. The cyclone should be as close to the gasifier as possible to keep the gas hot, might want to insulate the exhaust up to the cyclone. Too cool and you could get condensing in the cyclone and end up with a mess. I then built a preheat shroud around the cyclone for incoming air. So far the preheat shroud hasn’t cooled the gas to the dew point as SU advised me that it might… I’m very happy with the results. Gets out an amazing amount of particulate matter and so far has raised incoming air 150 to 200 degrees F from ambient in tests.

1 Like

Your oil bath filter. I have one on my system, I have taken all the oil out and run it dry.
The gas and air passing through the oil makes a vapor that the little soot that is still in the gas mixes with , this oil soot mix then coats everything and I suspect my valve stems and guide leading to the premature failure of my cylinder head !
Just my experance, it’s lot easier to clean out dry soot than oil/soot gunge !!!
It’s not pleasant stuff !
Thanks Patrick

Brian, I have been running a cyclone for years built from the same diagram in Pepe’s post. It is fantastic! It’s about as tall as Pepe’s as well. Every couple of months I clean out a couple of gallons of pure, dry soot. Actually, this past summer I finally got tired of messing around with a final filter after the cooling rails. There was never much of anything in it but bits of rust. I am now running a series of magnets and two filter disks 6" diameter, one is steel with 1/8" holes; the last is a piece of plastic furnace filter.
I kind of think that stainless pipes and cooler would solve the rust bits for good. The cyclone certainly collects the soot.

Hi All,
I started my cyclone adventure when I decided an hourglass hearth seemed to be the most logical choice for a structured char bed. I drew and put together a sample from cardboard for a test of reasonableness. I built a simple brake from angle iron and a 1 1/8" diam steel rod. I added a bend-o-meter gauge to insure a consistent bend per radius line. Don’t bend all at once. I went around 4 or 5 times before it came together. The smallest ID I could manage was the OD of an 1 1/4" threaded steel coupling, and I used a threaded end from an 1 1/4" pipe on the metal canister catch basin. It wasn’t quite a circle so I heated it and worked it to shape. It works great, albeit a slower process than rolling.
In the eighth picture where I set up to bend the pattern, the line up is critical and must be consistent. It takes some practice but the lines must be the contact point with the bar. Look where it meets and adjust up or down while maintaining a straight centerline with the bar. My picture shows the line at the top of the bar to stress the parallel need only, the actual contact point will be lower. The steel rod is removable.
I started with some tested numbers for my hearths and cyclones. They both work well so, I don’t see any reason to change them.
Hope this helps those that are wondering how I did it.


Thought you’d all appreciate my first ever cone before the bend-o-meter. In general do not over bend these first bends. Your cone will never bend true. Also more radii will give a smoother bend overall. These will always be many sided polygons.

Hi Patrick,
Thanks for the input. The picture I posted shows a bubbler type oil filter. The one I’m thinking about would only blow the smoke perpendicular onto the surface of the oil. I grew up with cars that only had oil bath filters and don’t remember problems of oil coating. Our fouled plugs were usually from over rich mixture and of course worn out engines burning oil. Maybe I’ll try foam or paper first.